# Body - Fields { #body-fields }

The same way you can declare additional validation and metadata in *path operation function* parameters with `Query`, `Path` and `Body`, you can declare validation and metadata inside of Pydantic models using Pydantic's `Field`.

## Import `Field` { #import-field }

First, you have to import it:

{* ../../docs_src/body_fields/tutorial001_an_py310.py hl[4] *}


/// warning

        return noFollow;
    }

    /**
     * Adds metadata to this response.
     *
     * @param name the name of the metadata
     * @param value the value of the metadata
     */
    public void addMetaData(final String name, final Object value) {
        metaDataMap.put(name, value);
    }

    /**
     * Gets the metadata map containing all metadata associated with this response.
     *

 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.maven.artifact.repository.metadata;

/**
 * Error while retrieving repository metadata from the repository.
 *
 */
@Deprecated
public class RepositoryMetadataResolutionException extends Exception {
    public RepositoryMetadataResolutionException(String message) {

 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

/**
 * Maven Repository Metadata model.
 */

        return Collections.unmodifiableList(new ArrayList<>(versions));
    }

    @Override
    public String pathOfLocalRepositoryMetadata(ArtifactMetadata metadata, ArtifactRepository repository) {
        return userLocalArtifactRepository.pathOfLocalRepositoryMetadata(metadata, repository);
    }

    @Override
    public String getId() {
        return userLocalArtifactRepository.getId();
    }

    @Override

 * under the License.
 */
package org.apache.maven.artifact.metadata;

import org.apache.maven.artifact.Artifact;

/**
 * Error while retrieving repository metadata from the repository - deprecated
 */
@Deprecated
public class ArtifactMetadataRetrievalException
        extends org.apache.maven.repository.legacy.metadata.ArtifactMetadataRetrievalException {

    /**
     * @param message a message

## OpenAPI 元数据 - 文档

要添加 OpenAPI 的元数据，包括许可证、版本、联系方式等，请阅读 [教程 - 元数据和文档 URL](../tutorial/metadata.md){.internal-link target=_blank} 文档。

## OpenAPI 自定义 URL

要自定义 OpenAPI 的 URL（或删除它），请阅读 [教程 - 元数据和文档 URL](../tutorial/metadata.md#openapi-url){.internal-link target=_blank} 文档。

## OpenAPI 文档 URL

    }

    /**
     * @throws Exception
     */
    @Test
    public void testGetIntFieldObject() throws Exception {
        final Field field = getClass().getField("INT_DATA");
        assertThat(FieldUtil.getInt(field), is(INT_DATA));
    }

    /**
     * @throws Exception
     */
    @Test
    public void testGetStringField() throws Exception {
        final Field field = getClass().getField("stringField");

 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.maven.artifact.repository.metadata;

/**
 * Error while installing repository metadata.
 *
 */
@Deprecated
public class RepositoryMetadataInstallationException extends Throwable {
    public RepositoryMetadataInstallationException(String message) {
        super(message);

            }
        }
    }

    private List<?> validationPluginExcludes(RepositorySystemSession session) {
        return (List<?>) session.getData().computeIfAbsent(PLUGIN_EXCLUDES_KEY, () -> parsePluginExcludes(session));
    }

    private List<String> parsePluginExcludes(RepositorySystemSession session) {